Russia’s President Vladimir Putin has accused the US of trying to draw his country into a war in Ukraine.
He said America’s goal was to use a confrontation as a pretext to impose more sanctions on Russia.
Mr Putin also said the US was ignoring Russia’s concerns about Nato alliance forces in Europe.
The US and its Nato alliance partners accuse Russia of planning an invasion of Ukraine, something Russia has repeatedly denied.
On Tuesday US Secretary of State Antony Blinken tweeted that the US was “committed to preventing a conflict that is in no one’s interest”.
In recent weeks Russia has moved about 100,000 troops – equipped with everything from tanks and artillery to ammunition and air power – to Ukraine’s border.
It comes eight years after the country annexed Ukraine’s southern Crimea peninsula and backed a bloody rebellion in the eastern Donbas region.
Moscow in turn accuses the Ukrainian government of failing to implement an international deal to restore peace to the east, where at least 14,000 people have been killed and Russian-backed rebels control swathes of territory.
Meanwhile, Ukrainian President Volodymyr Zelensky warned on Tuesday that a Russian invasion would “not be a war between Ukraine and Russia – this would be a war in Europe, a full-scale one”.
Speaking after talks with Hungarian Prime Minister Viktor Orban in Moscow, Mr Putin said: “It seems to me that the United States is not so much concerned about the security of Ukraine… but its main task is to contain Russia’s development. In this sense Ukraine itself is just a tool to reach this goal.”
Rivalry between Russia and the US, which still possess the world’s biggest nuclear arsenals, dates back to the Cold War (1947-89). Ukraine was then a crucial part of the communist Soviet Union, second only to Russia.
Mr Putin said the US had ignored Moscow’s concerns in its response to Russian demands for legally binding security guarantees, including a block on the Nato alliance’s further expansion to the east.
He suggested that if Ukraine were granted its wish to join Nato, it could drag the other members into a war with Russia.
“Imagine that Ukraine is a Nato member and a military operation [to regain Crimea] begins,” the Russian leader said. “What – are we going to fight with Nato? Has anyone thought about this? It seems like they haven’t.”
The US meanwhile insists it is fully committed to dialogue. Speaking after a call with Russian Foreign Minister Sergei Lavrov on Tuesday, US Secretary of State Blinken said he had emphasized US willingness to continue discussing “mutual security concerns”.
Earlier this week the US said it had received a written response from Russia to a US proposal aimed at de-escalating the crisis in Ukraine. But hours later Russia’s deputy foreign minister said that was not true and a source told Ria news agency it was still preparing a response.
In Ukraine itself on Tuesday, visiting UK Prime Minister Boris Johnson accused Mr Putin of effectively “holding a gun… to the head of Ukraine” and he called on the Kremlin to step back from a “military disaster”.
Mr Johnson warned that the UK would respond to Russian aggression with a “package of sanctions and other measures to be enacted the moment the first Russian toecap crosses further into Ukrainian territory”.
The UK has announced it is giving £88m ($119) to Ukraine to promote stable governance and energy independence from Russia.
Mr Zelensky called for sanctions to be introduced before any escalation, saying he would support any move by the UK to deal with “dirty money” allegedly linked to the Kremlin being laundered through the City of London.